Preventive antibiotic therapy of newborn human infants at risk for systemic infection (sepsis) occurs in large numbers of infants born in the U.S. Such therapy increases hospitalization stay for infants, temporary separation of newborns from their mothers, and exposes infants to antibiotics which are increasingly expensive and overused. If an infant is ill, such interventions are well justified; neonatal sepsis is a life threatening medical emergency. However, it is quite possible that greater than 85 percent of such infants are not infected. Rapid, accurate detection of the 15-20 percent of infected infants is the goal of this proposal. To this end, we will determine the utility of a DNA- based amplification assay for detecting bacterial or yeast DNA directly from blood samples obtained from neonates being evaluated for sepsis. The current standard of care is blood culture, but this method lacks sensitivity, and requires greater than or equal to 12 hr to 2 days to detect organisms. These problems are exacerbated further now that more infants are being born to mothers receiving intrapartum antibiotics for Group B Streptococcus colonization. Although antibiotic therapy for these women has decreased the incidence of neonatal GBS sepsis, the risk has not been eliminated completely, and it may actually undermine the chance of obtaining high quality blood culture results. This is because antibiotics within the infants' blood from intrapartum therapy may reduce recovery of culturable organisms, if present, making a negative culture result unreliable for ruling out sepsis. This creates a situation in which infants are unnecessarily treated with antibiotics. At Magee-Womens Hospital, approximately 1300 neonates are evaluated for sepsis annually. In the majority of cases (87 percent), the blood cultures are sterile. Despite this fact, infants are given antibiotics for greater than or equal to 48 hr. A more sensitive, reliable method of ruling out sepsis would markedly reduce prophylaxis of healthy infants. If this new assay, which is already known to take only 8 hr is more reliable than culture, it will result in a significant cost savings; reduction in hospital days, unnecessary antibiotic exposure and risk of developing drug resistance. In addition to these tangible benefits, there will be the benefit of reducing the emotional burden to mothers who must otherwise leave the hospital without their healthy new born infants, and eliminate the complication of how to continue breast feeding if the mother/infant pair is separated.